1. Field of the Invention
The present invention relates to a coalescer element and, more particularly, to a coalescer element with enhanced coalescence.
2. Discussion of the Related Art
Coalescers, sometimes in conjunction with separators, including inertial separators, settling devices, and separator cartridges, are generally utilized in industrial processes to separate several phases present in fluids, i.e., gases and/or liquids. In some instances such fluids constitute dispersions of two or more immiscible liquids such as oil and water. In other instances, such fluids constitute suspensions of liquid and/or solid particles in gas. In addition to separation, coalescers generally draw together or conglomerate smaller portions of one of the phases present in the fluid.
The spectrum of applications where coalescers have been used to remove minor amounts of a first phase, known as a discontinuous phase, from a second phase in which it is suspended, known as the continuous phase, covers a considerable range of situations. For example, coalescers may be utilized to remove water from compressed gas streams such as air, helium, hydrogen, nitrogen, carbon dioxide, and natural gas.
Coalescers may also be utilized to remove contaminants found in natural bodies of water such as oil spills. Additionally, coalescers may be utilized to separate small amounts of moisture, i.e., water, from petroleum based fuels, including gasoline, diesel and aviation fuels, such as kerosene.
In a coalescing process, for example, the coalescence of water from a petroleum based fuel, the fuel containing the water is passed through a coalescer comprising a coalescing medium. The fuel, which is the continuous phase fluid, passes through the medium and flows toward a first outlet. As the water, which is the discontinuous phase fluid, passes through the medium it tends to collect on the surface of the coalescing medium and form small droplets which are forced through the medium by the continuous phase fluid. The coalescing medium may be formed from or coated with a material which facilitates the formation of the droplets and the conglomeration of these small droplets into larger droplets. The larger water droplets are more easily removed via a second outlet and are less likely to be re-entrained into the fuel.
A limiting factor in the effectiveness or efficiency of the coalescing process in the re-entrainment of the droplets of the discontinuous phase fluid into the continuous phase fluid after they emerge from the coalescing medium. Re-entrainment may occur because of a number of reasons. One reason re-entrainment may occur is because the droplets of the discontinuous phase are too small and may be easily carried along by the potentially high flow rates of the continuous phase fluid to the continuous phase outlet. Accordingly, the smaller the droplets, the more likely the chance of re-entrainment. In addition, the smaller the droplets, the more likely the chance of the droplets penetrating a separator cartridge or any other type of separator, if a separator is utilized. Similarly, the larger the droplets, the less likely the chance of re-entrainment because they are less likely to be carried by the continuous phase fluid to the continuous phase fluid outlet and the less likely to penetrate into a separator.
Various mechanisms have been tried to increase the size of the droplets of the discontinuous phase fluid. For example, socks, foam, nettings, fuzzy woven or non-woven materials, or combinations thereof positioned over the coalescing medium have been utilized to increase the size of the droplets. However, in high surfactant conditions, the above-referenced materials or combination of materials which may be utilized, increase the size of the coalescing elements.